【最新】七年级数学下册 7.2第六课时 解方程组(加减法3)课件 华东师大版 课件,二元一次方程组的解法,七年级数学(下),加减法(3),【最新】七年级数学下册 7.2第六课时 解方程组(加减法3)课件 华东师大版 课件,解方程组:,3x - y = 3,4x+3y = 17.,+,得,解,3,得,x = 2.,即,即,32-y = 3,y = 3.,所以,x = 2,y = 3.,9x-3y = 9,4x +3y = 17.,13x = 26,将x=2代入,得,6-y = 3,-y = 3-6.,(1),消去y,或将x=2代入,得,42+3y = 17,8+3y = 17,3y =17-8,3y = 9,y = 3.,【最新】七年级数学下册 7.2第六课时 解方程组(加减法3)课件 华东师大版 课件,解方程组:,3x - y =3,4x + 3y = 17., - ,得,解,4,得,y = 3.,即,即,3x-3 = 3,所以,x = 2,y = 3.,12x - 4y = 12,12x + 9y = 51.,9y-(-4y) = 51-12,将y = 3代入,得,3x = 3+3,
